This application is based on French Patent Application No. 0007296 filed Jun. 7, 2000, the disclosure of which is hereby incorporated by reference thereto in its entirety, and the priority of which is hereby claimed under 35 U.S.C. xc2xa7119.
1. Field of the Invention
The present invention relates to suspension thrust bearings used in automobile vehicles in particular in telescopic suspension arms of the wheels that can pivot to steer the vehicle.
2. Description of the Prior Art
A suspension thrust bearing generally includes a top race and a bottom race with rolling members in the form of balls or rollers disposed between them.
The invention relates more particularly to suspension thrust bearings including at least one synthetic material cap in contact with one of the two races of the bearing.
The suspension thrust bearing is at the top of the suspension arm, between a bottom metal cup, which also provides a bearing seat for a suspension spring, and a top member fastened to the body of the vehicle. This is known in the art. The spring of the suspension device surrounds the piston rod of the damper piston, whose end is fastened to an elastic support block. The suspension thrust bearing enables relative rotation of the bearing cup for the spring, which is rotatable, and the elastic support block, which is fixed to the body of the vehicle. The suspension thrust bearing also transmits axial forces between the spring and the body of the vehicle. Relative angular movement between the bearing cup for the spring and the elastic support block results from pivoting of the wheel to steer the vehicle and/or compression of the suspension spring. For more information see French patent No. 2 779 096.
The suspension thrust bearings are located under the body of the vehicle and in the immediate vicinity of the wheels, which throw up polluting material that can penetrate into the bearings, especially in wet weather.
A device including one or two plastics material caps can be used. This is known in the art, for example from the documents U.S. Pat. No. 4,995,737 and EP-A-390 331. Each cap encloses one race and has axial retaining means cooperating with the other cap. The seal is then provided by lips on one of the caps rubbing on the other cap.
The caps are generally made from glass-fiber reinforced plastics material to give them the necessary strength and stiffness. This material is too rigid to provide a sufficiently effective seal. Force-fitting seals over the races of the bearing can also be envisaged, but in this case it is necessary to use seals with a metal armature, which is relatively costly (see for example the document JP 08-219 150).
The invention proposes a compact suspension thrust bearing that provides a good seal and cannot accidentally fall apart during handling or transportation prior to its permanent installation on the suspension arm.
The invention provides a suspension thrust bearing including a first race, a second race, a row of rolling members disposed between the two races, a cap fastened to the first race, and a sealing member fastened to a rotary or non-rotary member and adapted to cooperate with a respectively non-rotary or rotary surface, the sealing member including a seal that is initially separate from the cap, adapted to be mounted on the cap, has a bead adapted to be force-fitted in an annular groove in the cap, is disposed axially between the cap and the second race or another cap fastened to the second race, and has a lip adapted to come into rubbing contact with a bearing surface formed by a surface of the second race or of the other cap fastened to the second race.
The bearing surface in contact with the lip can be a substantially radial surface.
The seal preferably has a bead fixed into an annular groove in the cap. The diameter of the groove can be substantially equal to the outside diameter of the row of rolling members.
In one embodiment of the invention the first race has a radial portion adapted to partly overlap the bead. The radial portion locks the bead in the groove.
In one embodiment of the invention the surface of the rotary race is adjacent a concave surface forming a rolling path for the rolling members.
In one embodiment of the invention the cap has means for fastening it axially to the rotary race.
In one embodiment of the invention the cap has means for fastening it axially to the other cap.
In one embodiment of the invention the lip of the seal extends radially outward from the bead.
In one embodiment of the invention the lip of the seal extends downward from the bead in an assembled configuration of the bearing.
The seal is advantageously disposed radially between the rolling members and a substantially axial skirt. The skirt can be part of the cap.
In one embodiment of the invention the skirt is adapted to retain the second race or the other cap fastened to the second race.
A suspension thrust bearing is obtained whose overall radial and axial dimensions are not increased compared to prior art bearings, which provides a good seal and incorporates means for fastening the various components together.
The present invention will be better understood and other advantages will become apparent on reading the following detailed description of a few embodiments of the invention, which are described by way of non-limiting example and shown in the accompanying drawings.